Compositions and methods for assaying platelet reactivity and treatment selection

Abstract

Compositions and methods are provided for determining platelet reactivity where the levels of FcγRIIa on the surface of platelets is measured and if the levels of FcγRIIa are greater than a reference value, the platelets have enhanced reactivity.

What is claimed is: 
     
       1. A method of treating a selected subject at risk of thrombosis with an anti-thrombotic therapy, the method comprising:
 administering an anti-thrombotic agent that is an Adenosine diphosphate (ADP) receptor antagonist and/or a Protease-activated receptor (PAR) antagonist to the selected subject, wherein the subject is selected by detecting a level of copies of FcγRlla per platelet from the subject and comparing the level of copies of FcγRlla per platelet from the subject against a level of copies of FcγRlla per platelet from a disease-free individual, wherein a level increased by at least about 1.5-5 fold of FcγRlla per platelet identifies the subject as at risk of thrombosis and in need of anti-thrombotic therapy. 
 
     
     
       2. The method of  claim 1 , wherein the level of FcγRIIa is determined using an FcγRIIa specific reagent. 
     
     
       3. The method of  claim 2 , wherein the FcγRIIa specific reagent is an antibody or antigen binding fragment thereof. 
     
     
       4. The method of  claim 1 , wherein the level of platelet FcγRIIa is determined using an assay selected from the group consisting of flow cytometry, immunoassay, ELISA, western blotting, and radioimmunoassay. 
     
     
       5. The method of  claim 1 , wherein the level of FcγRIIa is determined using fluorometric or colorimetric assay. 
     
     
       6. The method of  claim 1 , wherein the level of FcγRIIa is determined using flow cytometry. 
     
     
       7. The method of  claim 1 , wherein the increased level of copies is at least about 2-5 fold of FcγRIIa per platelet. 
     
     
       8. The method of  claim 1 , wherein the increased level of copies is at least about 5-10 fold of FcγRIIa per platelet. 
     
     
       9. The method of  claim 1 , wherein the increased level of copies is at least about 10-25 fold of FcγRIIa per platelet. 
     
     
       10. The method of  claim 1 , wherein the step of detecting a level of FcγRIIa expressed on platelets comprises using a test device, wherein the test device comprises a liquid permeable material defining the following portions in capillary communication:
 a) a first portion that is the site for application of a liquid sample, comprising a liquid permeable medium, and an FcγRlla-binding conjugate; 
 b) a second portion comprising a liquid permeable medium; and 
 c) a third portion that is the site for detecting the binding of the FcγRlla-binding conjugate at the test site, the third portion comprising a liquid permeable medium having the FcγRlla fixed to the medium at the test site. 
 
     
     
       11. The method of  claim 10 , further comprising providing for the flow of the liquid from the site of application to the test site. 
     
     
       12. The method of  claim 10 , wherein anti-FcγRIIa antibody conjugate binding is detected by visual inspection. 
     
     
       13. The method of  claim 10 , wherein anti-FcγRIIa antibody conjugate binding results in the development of a color. 
     
     
       14. The method of  claim 10 , wherein the anti-FcγRIIa antibody conjugate specifically binds FcγRIIa. 
     
     
       15. The method of  claim 10 , wherein the first portion further comprises a control conjugate; and wherein the third portion comprises a control conjugate binder present at a control site for detecting the binding of the control conjugate. 
     
     
       16. The method of  claim 15 , wherein the analyte-binding conjugate and the control conjugate coat the surface of the liquid permeable membrane in the first portion. 
     
     
       17. The method of  claim 16 , wherein the coating is absent from the sample application site. 
     
     
       18. The method of  claim 10 , further comprising a fourth portion that acts as a wick, the fourth portion comprising sorbent material. 
     
     
       19. The method of  claim 10 , wherein the FcγRIIa-binding conjugate is an anti-FcγRlla antibody. 
     
     
       20. The method of  claim 10 , wherein the second portion comprises a liquid permeable material that acts as a filter to remove particulates. 
     
     
       21. The method of  claim 10 , wherein the first portion comprises a conjugate that specifically binds platelets. 
     
     
       22. The method of  claim 21 , wherein the conjugate that specifically binds platelets is one or more of an antibody to glycoprotein (GP) Ilb, GP Illa, GP V, GP lb, GP IX, a lysosomal membrane protein, and platelet endothelial cell adhesion molecule (PECAM). 
     
     
       23. The method of  claim 21 , wherein the conjugate that specifically binds platelets is one or more of anti-CD41, anti-CD41a, anti-CD61, anti-CD42d, anti-CD42b, anti-CD42a, anti-CD63, and anti-CD3 1. 
     
     
       24. The method of  claim 10 , wherein the second portion comprises an agent that alters the composition of the liquid as it contacts the second portion. 
     
     
       25. A method of treating a selected subject at risk of thrombosis with an anti-thrombotic therapy, the method comprising: administering an anti-thrombotic agent that is an Adenosine diphosphate (ADP) receptor antagonist and/or a Protease-activated receptor (PAR) antagonist to the selected subject, wherein the subject is selected by detecting a level of copies of FcγRlla on platelets in a biological sample of blood, plasma, or serum from the subject, and comparing the level of copies of FcγRlla per platelet from the subject against a level of copies of FcγRlla per platelet from a disease-free individual, wherein a level increased by at least about 1.5-5 fold of FcγRlla per platelet identifies the subject as at risk of thrombosis and in need of anti-thrombotic therapy.